Drive unit for an automatic washing machine



Feb. 28, 1967 H. RHEIN ETAL DRIVE UNIT FOR AN AUTOMATIC WASHING MACHINE Filed July 14, 1964 United States Patent 3,306,133 DRIVE UNIT FOR AN AUTOMATIC WASHING MACHINE Hans Rhein, Josef Keller, and Kurt Schuller, Schweinfurt am Main, Germany, assignors to Fichtel & Sachs A.G., Schweinfurt am Main, Germany, a corporation of Germany Filed July 14, 1964, Ser. No. 382,584 Claims priority, application Germany, July 19, 1963, F 40,279 8 Claims. (Cl. 74752) This invention relates to automatic washing machines and particularly to a multiple-speed drive unit for a washing machine and the like. 7

Automatic washing machines equipped with a drum rotating about a horizontal axis require a low-speed drive for tumbling the load during Washing, and a high-speed drive for drying the laundered material by centrifugal extraction. Automatic washers whose drums have an upright axis are commonly equipped with a central agitator which moves at a relatively low speed during washing whereas the drum is rotated at high speed during extraction.

In the initial stage of the centrifugal extraction process, the water-soaked laundered material is so heavy that an unbalanced distribution of the goods in the drum causes severe vibrations which are not readily controlled by conventional means when extraction is carried out at the high rotary speed required for adequate removal of Water.

The object of the invention is the provision of a threespeed drive for washing machines and similar equipment, the third speed being higher than the normal washing speed and lower than the usual extraction speed, but suflicient to remove a major portion of the water retained in the washed goods.

Another object is the provision of a three-speed drive unit which is not substantially heavier, bulkier, nor significantly costlier than the two-speed units employed heretofore for washing machines of the type described.

The known washing machine drive unit with the improvement of which this invention is concerned has been described, for example, in Patent No. 2,496,937. It is equipped with a two-speed motor coupled to a two-speed transmission and with a centrifugal governor which shifts the transmission from the lower to the higher transmission ratio when the motor is electrically switched from low-speed to high-speed operation in order to attain the required great difference in drum speed between washing and extracting operations.

One of the important features of this invention resides in a centrifugal transmission control which shifts the transmission from the lower to the higher transmission ratio when the motor is switched from low to high speed, but which is then locked and cannot shift the transmission to the lower ratio if the motor speed is subsequently reduced. Since the motor speed can be readily controlled by a time switch, switching the motor from low speed to high speed and subsequent return to low motor speed permits the drum to be rotated at an intermediate speed provided by motor rotation at low speed while the transmission operates at its high ratio.

Other features and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood from the following description of a preferred embodiment when considered with the attached drawing in which:

FIG. 1 shows elements of a washing machine equipped with a drive unit of the invention, the view being partly 3,306,133 Patented Feb. 28, 1967 VI C in side elevation, partly in elevational section, and partly diagrammatic; and

FIG. 2 shows a detail of the machine of FIG. 1 in front elevation.

The washing machine and its controls have been shown only to the extent necessary for an understanding of their cooperation with the drive unit with which this invention is more particularly concerned. The drive unit consists mainly of an electric motor 10, of the switch-gear 12 for the motor, a gear transmission 14, and a transmission control device 16.

The motor 10 is of the dual-winding type in which the number of effective poles may be changed by external switches to vary the speed of the motor drive shaft 18 in a ratio of 1:2. A transmission housing 20 attached to the motor frame encloses planetary reduction gearing 22. The input shaft 24 of the planetary gearing is connected to the drive shaft 18 of the motor by a flexible coupling 26. A sun gear 28 is fixedly mounted on the Shaft 24. An internal ring gear 30 is fixedly attached to the housing 20, and a planet carrier 32 carries two planet gears 34 which simultaneously mesh with the sun gear 28 and the ring gear 30.

The planet carrier 32 is coaxially connected to a tubular output shaft 38 of the transmission 14 by an overrunning clutch 36 of a type known in itself. The clutch can transmit torque from the carrier 32 to the shaft 38, but cannot transmit torque from the shaft to the carrier. The shaft thus may rotate freely at speeds higher than that of the planet carrier 32. The shaft 38 extends outward of the housing 20 and coaxially receives a portion of the input shaft 24 therein.

The enlarged free end 40 of the input shaft projects axially beyond the tubular output'shaft 38. The annular end portion 42 of the latter has a cylindrical face 41 of somewhat smaller diameter than that of the free end 40. A helical coupling spring 44 is coaxially attached to the free end 40 of the input shaft 24. In the position of the unit illustrated in FIG. 1, a portion of the coil is axially coextensive with the face 41, but radially at a small distance therefrom. A straight end portion 46 of the spring 44 extends radially away from the end portion 42 of the output shaft 38. a

A tubular centrifugal Weight 48 is slidably mounted on the straight spring portion 46. As better seen in FIG. 2, the weight 48 has a lateral notch 50. The weight is normally held near the common axis of the shafts 24, 38 by a helical tension spring 49. A pin 52 is fixedly mounted on the output shaft 38 and extends therefrom in a radial direction. The free end 54 of the pin 52 is bent into an axial course and clears the Weight 48 when the shafts 24, 38 rotate relative to each other While the device is in the position shown in FIG. 1.

The output shaft 38 carries a pulley 56. A V-belt 58- is trained over the pulley 56 and over a similar pulley 60' on the shaft of a horizontal Washing machine drum 64 which is journaled in a bearing 62 of the washing machine housing, not otherwise shown.

The switchgear 12 of the motor 10 is illustrated in a conventional manner. It includes two switches 66, connected to a non-illustrated source of electrical current and respectively in circuit with the low-speed and highspeed windings of the motor 10. The switches may be manually operated by means of respective actuating members 68, 72 and are also arranged for electro-magnetic actuation in a conventional manner. A timing switch 74 has a starter button 76 and is operated by a synchronous motor in a conventional manner after being started. The

timing switch 74 is connected in circuit with the motor switches 66, 70 for operating the same in timed sequence.

The aforedescribed washing machine is operated in the following manner:

To start slow rotation of the drum 64 for washing, the switch 66 is actuated by means of the member 68. The motor rotates the drive shaft 18 at low speed, and the sun gear 28 rotates at the same slow speed. The planet carrier 32 rotates at an even slower rate, and this lowest speed of which the drive unit is capable is transmitted by the clutch 36 to the output shaft 38. The low speed of the drive shaft 18 is transmitted by the input shaft 24 to the centrifugal weight 48, but the centrifugal forces generated cannot overcome the restraint of the spring 49.

The pulley 56 rotates at the low speed of the drive unit which results from the lower speed of the motor 10 and the lower transmission ratio of the planetary gearing 22. The drum 64 is rotated at a speed suitable for tumbling laundry during washing.

If the load in the drum is light so that vibration is not to be expected, the washed material may be directly dried by high speed extraction. The switch 70 is closed by means of the actuating member 72. The drive shaft 18 and the coupled input shaft 24 of the transmission are thereby rotated at the higher speed of the motor 10. The mass of the centrifugal weight 48 and the spring 49 are matched in such a manner that the centrifugal forces generated by the higher motor speed can overcome the spring 49, and the weight 48 moves radially outward into the path of the pin end 54 which then engages the notch 50 as shown in FIG. 2.

Because of'the initially slower rotation of the tubular output shaft 38, the pin 52 prevents the weight 48 and the straight end portion 46 of the spring 44 from rotating at the higher speed of the input shaft 24. The coupling spring 44 is tightened about the face 41 of the output shaft and drives the output shaft at the speed of the input shaft 24. Free rotation of the output shaft 38 at a speed higher than that of the planet carrier 32 is made possible by the overrunning clutch 36.

The ensuing rotary speed of the drum 64 is the highest available with the drive unit illustrated, the motor 10 running at its higher speed, and the transmission being shifted into the higher one of its two transmission ratios.

With a full load in the drum 64, enough water may be extracted at intermediate speed to permit removal of additional water at high speed without causing vibrations of undesirable amplitude due to eccentric loading. To operate the drive unit at its intermediate speed, the starting button 76 of the time switch is pressed, and the timing motor of the switch is thereby started. The contacts of the switch 74 are set in such a manner that the magnetic actuator in the switch 70 is first energized for a period which may be very brief, yet sufficient to cause engagement between the pin end 54 and the notch 50 as described hereinabove. The transmission is thereby locked in its higher transmission ratio at which the input shaft 24 and the output shaft 38 rotate in unison.

The switch 70 is then opened by the timing switch 74, and the switch 66 is actuated, whereby the motor speed is reduced to its lower value. Torque still being transmitted from the drive shaft 18 of the motor 10 to the gear transmission 14, the centrifugal weight 48 is being urged toward the pin 52 in the direction of the arrow in FIG. 2, the free end 54 of the pin cannot escape from the notch 50, and the coupling spring 44 remains in tight engagement with the face 41 of the output shaft until the motor 10 is stopped.

The drum 64 rotates at the intermediate speed determined by the lower speed of the motor 10 and the higher transmission ratio of the gear transmission 14.

After a suitable time, closing of contacts on the timing switch 74 may switch the motor 10 to its higher speed, and the laundered goods, partly extracted at the intermediate drum speed, are fully dried at the highest drum speed. When the motor 10 is stopped, the spring 44 unwinds sufficiently to permit its end 54 to be released from the notch 50 whereupon the weight 48 is returned to the position shown in FIG. 1 by the spring 49.

It will be appreciated that the switch 74 may be a section of the timing mechanism of an automatic washing machine which also actuates solenoid-operated water intake and drain valves in a conventional manner. Those skilled in the art will readily modify the switch gear illustrated to operate the drive unit sequentially at low, intermediate, and highest speed in timed sequence, the intervention of an operator being limited to pushing the button 76.

In a manual or semi-automatic washing machine, the switch 74 may be omitted together with the electromagnetic actuators in the switches 66, 70. Rotation of the drum 64 at intermediate speed may be set by manually operating the actuating members 68, 72 in the sequence described hereinabove with reference to the timing switch 74.

The invention has been described with specific reference to a washing machine having a drum arranged for rotation about a horizontal axis, and therefore not requiring an agitator. A washing machine having an agitator may be equipped with the drive unit of the invention in a manner conventional in itself, and the drive unit may be connected automatically or manually to the agitator and drum as needed for operation in the usual manner.

The drive unit may be stopped either by actuating the members 68, 72, or by the timing switch 74 at the conclusion of its timing cycle, as is conventional.

The illustrated transmission control device 16 has been found particularly suitable for use in a washing machine because of its ruggedness and reliability, but other centrifugally actuated clutches or couplings equipped with automatic locking means for locking the controlled transmission in one of its transmission ratios regardless of the centrifugal forces available may be substituted as disclosed in more detail in the commonly assigned copending application Serial Number 3'61,698, filed on April 22, 1964, now Patent No. 3,262,533.

Various other modifications are contemplated and may obviously be resorted to by those skilled in the art without departing from the spirit and scope of the invention as hereinafter defined by the appended claims, as only a preferred embodiment thereof has been disclosed.

We claim:

1. A drive unit for a washing machine and the like, comprising, in combination:

(a) a dual speed motor having a rotatable drive member and adapted selectively to rotate said drive member at a lower speed and a higher speed;

(b) switchgear connected to said motor for controlling the speed of saiddrive member;

(c) a dual speed transmission having an input member connected to said drive member for transmission of torque from said motor to said transmission and a rotatable output member, and changeable between a lower and a higher transmission ratio from said input member to said output member;

(d) centrifugal transmission control means responsive to rotation of said drive member at said higher speed for causing said transmission to change from said lower to said higher transmission ratio; and

(e) locking means responsive to torque transmitted from said motor to said transmission at both speeds of said motor for preventing changing of said transmission from said higher to said lower transmission ratio.

2. A drive unit as set forth in claim 1, wherein said transmission includes first and second transmission members operatively connected for simultaneous rotation at different respective speeds, said transmission control means include a centrifugally actuated coupling movable between two positions in which said coupling respectively couples said output member to said two transmission members in response to the rotary speed of said drive member, and said locking means include means for preventing movement of said coupling from one of said positions to the other position.

3. A drive unit as set forth in claim 2, wherein said transmission control means further include overrunning clutch means interposed between the first transmission member, said member rotating at the lower one of said different speeds, and said output member for transmitting torque from said first transmission member to said output member while permitting rotation of said output member at a rotary speed higher than the speed of said first transmission member.

4. A drive unit as set forth in claim 3, wherein said transmission includes planetary gearing having a sun gear constituting said input member, a stationary ring gear, a rotatable planet carrier, and planet gear means rotatable on said carrier and simultaneously meshing with said sun gear and said ring gear, said planet carrier constituting said output member, said sun gear and said planet carrier being said first transmission member and said second transmission member respectively.

5. A drive unit as set forth in claim 3, wherein said transmission control means further include a centrifugal weight member mounted on said second transmission member for rotation therewith about an axis, and for radially outward movement into an operative position in response to centrifugal forces generated by said rotation, yieldably resilient means normally urging said weight means to move radially toward said axis, and engageable coupling means on said output member and on said second transmission member, said coupling means being arranged for engagement in response to said radially outward movement of said centrifugal weight member.

6. A drive unit as set forth in claim 5, said locking means including a locking member mounted on said output shaft for circumferential abutting engagement with said centrifugal weight member when said output shaft and said second transmission member rotate at different speeds while said centrifugal weight member is in said operative position thereof, said centrifugal weight member being formed with a circumferentially open recess for receiving said locking member and having a wall in said recess for engagement with said locking member under the force of said resilient means, whereby said centrifugal weight is prevented from moving toward said axis.

7. A drive unit as set forth in claim 6, wherein said coupling means include a helical spring member and an engagement face about the axis of said spring member, said spring member and said face being respectively fastened on said output member and on said second transmission member, said spring member being normally radially spaced from said face, and connected to said centrifugal weight member for tightening about said face when said weight member is engaged by said locking member while said output shaft and said second transmission member rotate at different speeds.

8. In a washing machine, in combination:

(a) a dual speed motor having a rotatable drive member and adapted selectively to rotate said drive member at a lower speed and a higher speed;

(b) switchgear connected to said motor for controlling the speed of said drive member;

(c) a dual speed transmission having an input member connected to said drive member for transmission of torque from said motor to said transmission and a rotatable output member, and changeable between a lower and a higher transmission ratio from said input member to said output member;

(d) centrifugal transmission control means responsive to rotation of said drive member at said higher speed for causing said transmission to change from said lower to said higher transmission ratio:

(e) locking means responsive to torque transmitted from said motor to said transmission at both speeds of said motor for preventing changing of said transmission from said higher to said lower transmission ratio;

(f) rotatable drum means adapted to receive a load of material to be laundered and dried; and

(g) motion transmitting means interposed between said output member and said drum means for rotating the same when said motor rotates said drive member.

References Cited by the Examiner UNITED STATES PATENTS 2,496,937 2/1950 Edwards 74-472 2,705,065 3/1955 Kloss 192-41 3,003,090 8/1961 Neyhouse et al. 74472 DAVID J. WILLIAMOWSKY, Primary Examiner. L. H. GERIN, Assistant Examiner. 

1. A DRIVE UNIT FOR A WASHING MACHINE AND THE LIKE, COMPRISING, IN COMBINATION: (A) A DUAL SPEED MOTOR HAVING A ROTATABLE DRIVE MEMBER AND ADAPTED SELECTIVELY TO ROTATE SAID DRIVE MEMBER AT A LOWER SPEED AND A HIGHER SPEED; (B) SWITCHGEAR CONNECTED TO SAID MOTOR FOR CONTROLLING THE SPEED OF SAID DRIVE MEMBER; (C) A DUAL SPEED TRANSMISSION HAVING AN INPUT MEMBER CONNECTED TO SAID DRIVE MEMBER FOR TRANSMISSION OF TORQUE FROM SAID MOTOR TO SAID TRANSMISSION AND A ROTATABLE OUTPUT MEMBER, AND CHANGEABLE BETWEEN A LOWER AND A HIGHER TRANSMISSION RATIO FROM SAID INPUT MEMBER TO SAID OUTPUT MEMBER; (D) CENTRIFUGAL TRANSMISSION CONTROL MEANS RESPONSIVE TO ROTATION OF SAID DRIVE MEMBER AT SAID HIGHER SPEED FOR CAUSING SAID TRANSMISSION TO CHANGE FROM SAID LOWER TO SAID HIGHER TRANSMISSION RATIO; AND (E) LOCKING MEANS RESPONSIVE TO TORQUE TRANSMITTED FROM SAID MOTOR TO SAID TRANSMISSION AT BOTH SPEEDS OF SAID MOTOR FOR PREVENTING CHANGING OF SAID TRANSMISSION FROM SAID HIGHER TO SAID LOWER TRANSMISSION RATIO. 